EL CAJON — A semi-truck with a flatbed trailer that was carrying empty propane tanks caught on fire late Tuesday afternoon on the transition from eastbound Interstate 8 to northbound state Route 67, snarling rush-hour traffic.

The driver said that about 4 p.m., the truck's engine failed, causing a fire, said Officer Brian Pennings of the California Highway Patrol. The driver tried to pull as far off the road as possible, Pennings said.

The driver was not injured and did not have passengers. He was headed to Ramona after starting in Eagle Pass, Texas, the officer said.

The semi was fully loaded with large propane tanks used for residential and commercial purposes, Pennings said.

Fire crews on the scene were dousing flames from diesel fuel and trying to prevent the blaze from spreading to nearby eucalyptus trees.

There were reports of loud explosions, but Pennings said the sounds came from the explosion of the truck's front tires, not from the empty tanks.

Eastbound 8 in the area of the accident was reopened before 5 p.m., but westbound I-8 to northbound state Route 67 and the Magnolia Avenue on-ramp to northbound SR-67 were expected to be closed for about another hour for cleanup, Pennings said.